Mixing valve with adjustable regulating elements and central chamber

ABSTRACT

A mixer for a fluid flow in a pipe connection, especially for homogenizing a multiphase flow, has a housing to be inserted in the pipe connection for the fluid to flow through. In the housing there are at least one and preferably two or more adjoining and individually displaceable regulating elements having cooperating wall portions with flow passages. At an upstream side radial flow passages cause the fluid to converge into a central chamber. In the cooperating wall portions, a number of flow channels can be aligned or misaligned with one another and/or the inlet and outlet openings to regulate and control flow by movement of the regulating elements. The regulating elements also define a full cross-section opening at 90° to the flow passages, which can clear the passage between the inlet and outlet for passage of a pipe pig.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION

This invention relates to a mixer for mixing the components of a fluidflow in a pipe connection, in particular a multi-phase flow as e.g.fluids produced from an oil or gas well, comprising a housing adapted tobe inserted in the pipe connection and to have the fluid flow runningtherethrough, whereby the housing comprises an inlet and an outletopening respectively.

SUMMARY OF THE INVENTION

The invention has primarily been developed in connection withmeasurement of multi-phase mass flow, whereby the components can be e.g.oil, water and gas. By multi-phase flow there is here also meant casesin which only two phases are concerned, e.g. a liquid and a gas, or evenwhen there is question of two liquids in one phase being conductedthrough the same pipe or the like. It will be realized however, that themixer to be described in the following description, may also have otherpractical uses than in connection with mass flow measurement. Moreoverwhen pipe connections are referred to here, this comprises both quiteregular pipes connected to the input and output sides respectively ofthe mixer, and pipes or connections that can be more or less integratedinto other equipment or devices, e.g. valves, pumps and so forth.

A mixer as stated in the introductory paragraph above, according to thisinvention has novel a specific features comprising in the first placethat in the housing there is provided at least one moveable regulatingelement with wall portions associated with at least a downstream side ofthe housing and provided with a number of through-going flow channels,each of which has a substantially smaller cross-sectional area than theflow cross-sectional area at the inlet and outlet opening respectively,and that the regulating element is adapted to be moved in relation tothe housing.

According to the fundamental solution stated above, the invention makespossible two main aspects, of which one aspect in the principle is baseson a rotational symmetry and mutual displacement of the regulatingelements primarily by a rotary movement thereof. Another main aspect isdirected to a basic planar arrangement of one or more regulatingelements, whereby said movement thereof takes place by translationalmovement. The invention also comprises a measurement apparatus for massflow as mentioned above, and the apparatus is based on a combinationwith the mixer described. A particular embodiment of the mixer accordingto the invention is intended for use in a freezing plant, heat pumpsystem or the like as a gas-liquid distributor in association with anevaporator.

In the claims there are also recited additional novel and specificfeatures related to both the mixer and the measurement apparatus.

The mixer according to the invention involves advantages inter alia bymaking possible control, either discretely by using only one or possiblyseveral regulating elements, or continuously so that at any time it canbe adjusted to the most favorable regulating position, with a resultingfavorable degree of opening. This means that the no-slip condition to ahighest possible degree can be fulfilled over a wide range of flowvelocities. According to an embodiment the mixer can be set in aparticular position (pigging position) that makes it possible to run apipe pig therethrough. Moreover the mixer can be so designed that it ispossible to mount it at any orientation being convenient in practice.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description the invention shall be explained moreclosely with reference to the drawings, in which:

FIG. 1 shows an example of a first embodiment of the mixer according tothe invention, as seen in axial longitudinal section normally to acommon axis of rotation in the mixer,

FIG. 2 shows the exemplary embodiment in FIG. 1, here also in axiallongitudinal section, but coincident with said common axis of rotation,

FIG. 3 shows a cross section of the mixer in FIG. 1 through the commonaxis of rotation, and

FIG. 4 somewhat simplified shows a second embodiment of the mixeraccording to the invention in longitudinal section through a portion ofa housing with two regulating elements therein,

FIG. 5 shows a longitudinal section as in FIG. 3, but normally to theplane of section in FIG. 4,

FIG. 6 shows an enlarged detail of the longitudinal section in FIG. 4,with the two regulating elements in a mutual position giving a maximumopening of the flow channels,

FIG. 7 in a sectional view as in FIG. 3 shows a particular embodimentfor employment in freezing plants, heat pump systems or the like,

FIG. 8 shows a modification of the embodiment of FIG. 1 and 2,

FIG. 9 shows another modification of the embodiment of FIG. 1 and 2, and

FIG. 10 shows a third modification of the embodiment of FIG. 1 and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 and 2 of the drawings the pipe connection or main pipeconcerned is represented by two pipe pieces 1A and 1B, which by means offlange connections 3A and 3B respectively, are connected to a housing 2for the mixer, whereby the direction of fluid flow through the mixer isindicated with arrows F1 and F2 in FIG. 1. The housing 2 has an interiorwall 21 that is substantially cylindrical and is broken by an inletopening 22 and an outlet opening 23 respectively, which in turn areleading directly to the respective flange connections 3A and 3B.

In the housing 2 there are provided two regulating elements 4 and 5which are co-axial and both have a cylindrical shape as the housing 2.These regulating elements 4 and 5 are individually rotatable in housing2 and at the cylindrical casing or wall portions have perforations inthe form of through-going flow channels upstream as shown at 6A and 6B,and downstream as shown at 7A and 7B. Between the inner wall 21 inhousing 2 and the outside of one regulating element 5, and moreoverbetween the inside of element 5 and the second regulating element 4,there are provided seals for the required fluid sealing. The common axisAX of housing 2 and the pair of regulating elements 4 and 5, in thisexample is oriented at a right angle to the general through-flowdirection of the multi-phase flow, i.e. the longitudinal axis in FIG. 1and 2. Embodiments may be contemplated however, wherein the commonrotational AX and the longitudinal axis F1-F2 are not exactly normal toeach other, but in all cases the common axis will lie broadlytransversally to the longitudinal axis.

As to the shape of the regulating elements these need not be fullycircular cylindrical as illustrated in the drawings, but can e.g. alsobe spherical, i.e. in principle the elements are in the form ofrotational bodies. The casing or wall portions being provided with theflow channels 6A, B, 7A, B as referred to, are shown with acomparatively large wall thickness, which can be considered in relationto the flow channels, which preferably should have a substantiallylarger length than lateral dimensions.

At the upstream side the input flow channels 6A and 6B at the wallportions facing each other on the regulating elements 5 and 4,respectively, have a convergent orientation, so that they have adirection generally towards a central region within housing 2, aconcentrated converging point being indicated exactly at theintersection between the common axis AX and the longitudinal axis F1-F2.This is to be considered as a more or less idealized case. At the otheror downstream side the outgoing flow channels 7A and 7B are shown with aparallel orientation corresponding to the through-flow direction orlongitudinal axis F1-F2. At this point it is remarked that by displacingthe two regulating elements 4 and 5 from the rotary position they haveaccording to the drawings, the configuration and orientation of therespective flow channels will of course be changed. In the rotaryposition shown in the drawings the flow channels both upstream anddownstream are at one hand aligned with each other and on the other handcentered with respect to openings 22 and 23, so that the fluidthrough-flow can take place with the least possible flow resistance.Thus the drawings show the mixer in a fully open position, where thechannels constitute a continuous and edge-free flow path through thecasing or wall portions of the regulating elements. If the mixing effectaimed at is not obtained with this configuration, one or both regulatingelements must be rotated so that the degrees of opening between theelements will be smaller. This results in a higher fluid velocity and abetter fluid mixing in the passage between the elements, but also ahigher flow resistance (pressure drop).

As will be seen from FIG. 3 the flow channels in this example, e.g.channels 7A, are designed with a circular cross section. According toFIG. 1 and 2 the cross section is the same throughout the whole lengthof each channel. However there are many possibilities of variation asregards the design of the flow channels, whereby one possibility is thatthese can have a more flattened or slit like cross-sectional shape, suchas with the largest lateral extension in the circumferential directionof the wall portions of the regulating elements. Further the channelscan be designed with a certain conicity in the longitudinal direction(see FIG. 10), perhaps in particular with a certain nozzle effect at theoutlet ends towards the central space in housing 2, and towards theoutlet opening 23 respectively from the housing. The flow channels 6A,6B, 7A and 7B shown, have an approximate regular distribution over thetotal flow cross section of openings 22 and 23 as well as the adjoiningpipe pieces or connections 1A and 1B, and such a regular distribution isconsidered to be the most favorable arrangement. This in particularapplies to the output flow channels 7A and 7B. Under specialcircumstances however, it can be convenient to deviate from the regulardistribution, in particular at the upstream side of the mixer. There isalso a reason to note that each of the flow channels described, has across-sectional area being substantially smaller than the totalcross-sectional area referred to with respect to openings 22 and 23. Forthe purpose of obtaining a larger capacity, i.e. a smaller flowresistance through the mixer, housing 2 can be designed with an expandedflow cross section towards one or both openings 22 and 23, so that therespective wall portions perforated with channels in each of the tworegulating elements 4 and 5, could be enlarged correspondingly in area.

Still another possibility with respect to the shape of the flow channelsconsists in that these can have unequal cross sections in the twocooperating regulating elements. FIG. 9 shows this modified embodiment,which corresponds to FIG. 1 except for the outer regulating element 5Chaving flow channels 6C and 7C with expanded cross sections, which meansthat they have larger cross sections than cooperating channels in theinner, adjacent regulating element 4. This involves inter alia, aregulating position for large flow velocities, where the regulatingelement 5C with the largest flow cross section is set in an operativeposition, i.e. mixing position, whereas the other regulating element 4is set in its pigging position, i.e. with its large bore (to bedescribed below) in the through-running position. At low flow velocitiesthe regulation can be the opposite, i.e. with the narrower flow channelsin mixing position and the larger flow channels rotated into aninoperative position. These variants and regulating positions show thatthe mixer can be designed with only one regulating element, e.g.provided thereby that the regulating elements 4 and 5 in FIG. 1-3 areintegrated into one single element.

From FIG. 2 and 3 it is seen that the regulating element 4 has a spindle14 and the regulating element 5 has a tubular spindle 15 being co-axialto spindle 14, so that rotation of the regulating elements mutually andwith respect to housing 2 can be effected. In the simplest case therotation can take place by means of manually operated controls, orpossibly by means of drive devices such as actuators or the like, asbeing known e.g. in connection with valve operations. Spindles 14 and 15extend out through a top cover 2A on housing 2.

With the structure described the degree of opening of the mixer can becontrolled by rotating the inner regulating element 4 in relation to theouter regulating element 5, so that the flow channels through the wallportions of the elements are displaced with respect to each other. As aresult there will be a larger or smaller narrowing of the flowcross-sectional area at the wall portions facing each other, i.e. at theinterface between the two regulating elements, depending on the relativerotational position established. At a sufficiently large mutual rotationof the regulating elements, the passage through the flow channels willbe completely closed.

In addition to the above mentioned, relatively narrow through-flowchannels the two regulating elements 4 and 5 have bores 4A, 4B and 5A,5B respectively, of diameter corresponding to the pipe diameter and theopenings 22 and 23 (FIGS. 1 and 3). These bores have an axis lyinggenerally at a right angle to the central axis of the respective wallportions with the flow channels. Thus, when the mixing function referredto shall not be established, i.e. with the mixer in the angular positionas shown in the drawings, both regulating elements 4 and 5 in common canbe rotated to a position in which the bores 4A, 4B, 5A, 5B coincide withopenings 22 and 23. This leads to a substantially free and straight pipesection which inter alia makes it possible to run a pipe pig through thehousing. For obtaining such a smooth through passage the housing 2 isprovided with a plug-like core member 12, which can be adapted tosealingly cooperate with the internal side of regulating element 4 i.e.at the cylindrical outer wall 12A of the core member. Through the coremember there is shown a bore 12B preferably aligned with and providedwith the same flow cross section as the inlet opening 22 and the outletopening 23.

The function of the mixer as described thus far, has to a large extentappeared from the preceding description, but at this point the followingis additionally remarked: The forms of flow to be handled by the mixercan be rather arbitrary and varying, since there may be the question oflaminar flow, plug flow, annular flow or dispersed flow, bubble flow orso-called churn flow. With some types of multi-phase flow a liquidcomponent in particular will be located at the bottom of the input pipe1A, whereas other components fill the remaining part of the flow crosssection. The convergent orientation of the input flow channels 6A-6B asdescribed, in such a situation will contribute to lifting the liquidcomponent from the bottom of the pipe upwards, whereas gas or similarfluid components being located in the higher cross-sectional portions ofpipe 1A and inlet opening 22, will be urged down towards the centralregion of the housing, i.e. within the bore 12B. This causes e.g. thetwo phases gas and liquid in such an incoming multi-phase flow to bespread over the flow cross section at the same time as an effectivemixing takes place in the central region mentioned above. The liquid-gasmixture is further pressed out through the parallel outgoing flowchannels 7A-7B at the downstream side of the mixer, which leads to afurther homogenizing of the fluid components over the full flow crosssection. Thus from the outgoing flow channels in this example, therewill be discharged a mixture in which the liquid phase or phases arefinely distributed in the gas, or depending on the proportion of gasfraction, the gas is finely distributed in the liquid or liquid mixture.

At the downstream side and in the pipe piece 1B connected to the mixer,there will accordingly be a flow in which the fluids are very well mixedand where the local gas fraction is approximately the same over thewhole pipe cross section. Besides the two or three phases being presentwill have average velocities being very close to each other, i.e. nearthe no-slip condition. Adjustment of the degree of opening in the mixerby rotating the two regulating elements 4 and 5 in relation to eachother, makes it possible to optimize the flow pattern so that theno-slip condition between liquid and gas will be fulfilled to a highestpossible degree.

For the purpose of the primary use of the mixer described above, inconnection with mass flow measurement as mentioned previously, there isin FIG. 2 at 30 indicated a radial plane downstream of the actual outletopening 23 (and the mouth of the flow channels 7B), where a fractiongauge can be adapted to sense the magnitude or parameter of interest.The phase fractions may also be determined by measurement locally withinthe flow channels in the outer regulating element 5. At the location orthe plane indicated at 30 the condition of equal velocity of thedischarged liquid and gas will be best fulfilled under manycircumstances. E.g. the fraction gauge can be a multi-energy gammadensitometer that measures the fractions of each individual fluid phasebeing present in the outgoing multi-phase flow.

Moreover in FIG. 2 there is shown a differential pressure sensor 9 beingadapted to measure the pressure drop ΔP_(m) across the mixer, i.e. witha connection to the inlet at flanges 3A or opening 22 and a connectionto the outlet at flanges 3B or opening 23. A more preferred upstreamconnection can be made, however, centrally within housing 2. Accordinglypressure sensor 9 will perform a differential pressure measurement overthe outlet of the mixer and not over the mixer as a whole. In thissection or part of the mixer the fluids are well mixed and the no-slipcondition is substantially fulfilled. The most substantial portion ofthe pressure drop measured, will of course be present between theupstream side of channels 7A and the downstream side of channels 7B. Thefriction contribution of this pressure drop is proportional to theaverage density ρ_(m) of the fluid mixture and to the square of thevelocity U_(m) of the mixture. By adjustment of the relative rotationalposition or angle between the two regulating elements 4 and 5, thepressure drop over the whole mixer is controlled, and simultaneously theflow conditions are changed so that the most favorable flow conditionsat any time are obtained.

The average density is given by the densities and area fractions of thefluids. This together with the pressure drop measurement in unit 9 givesthe velocity of the mixture. The mass flow of each individual fluidcomponent then is found as the product of the fluid density, areafraction, pipe cross section and common velocity. This determination andcalculation of mass flow is based upon principles being known per se,but anyhow shall be explained somewhat more in detail below.

Mass flow (in kg/s) of phase no. i is given by:

    M.sub.i =p.sub.i A.sub.i U.sub.m                           (1)

whereby

ρ_(i) =density of fluid no. i (kg/m³),

A_(i) =cross-sectional area of fluid no. i and

U_(m) =the average velocity (m/s) of the mixture.

In order to be able to employ the mixer described above, for measuringmass flow in multi-phase flow, the mixer must be used in combinationwith a fraction gauge. By means of a fraction gauge it is possible todetermine the fractions of each individual fluid, i.e.

    γ.sub.i =A.sub.i /A                                  (2)

Here A_(i) is the area being covered by fluid no. i, and ##EQU1## isequal to the pipe cross section.

The fraction gauge is to be positioned where the fluids are well mixed.This can be at the downstream transition between regulating elements 4and 5, within one of elements 4 and 5, or immediately downstream of theoutlet opening, e.g. at 30 in FIG. 2 as mentioned above.

Such a fraction gauge for oil and water can e.g. be a multi energygamma-densitometer (having two energy levels, where the decaycoefficient of the gamma rays is different for oil and water withrespect to at least one energy level) or a single energygamma-densitometer in combination with an impedance gauge.

The friction contribution of this differential pressure, as calculatedfrom measurement with unit 9 and with compensation for static pressuredrop (the gravitation contribution), is proportional to the averagedensity of the mixture and the square of the velocity of the mixture:##EQU2## so that the average velocity of the mixture will be ##EQU3##ρ_(m) =the average density (kg/m³) of the mixture ΔP_(m) =thedifferential pressure over the mixer (Pa)

a=the degree of opening=the lumen of (?) the channels/maximum lumen

Re=Reynolds number, being representative of the channels giving thelargest contribution to the differential pressure measured,

k(a, Re)=a factor being calibrated against the degree of opening andReynolds number,

The average density of the mixture ##EQU4## where ρ_(m) =density offluid no. i and

γ_(i) =the area fraction of fluid no. i (given by equation 2).

It is obvious that the choice of measuring device for the fractionmeasurements and the actual arrangement of such a gauge in associationwith the outlet from hosing 2, can be varied in many ways in relation towhat is described and illustrated here. If e.g. a two phase flow isconcerned, the fraction gauge can be an electrical capacitance elementinstead of being a gamma-densitometer. The position of the measuringdevice can be relatively close to the outlet opening 23, as indicated as30, or the distance from the opening can be larger than illustrated inFIG. 2, e.g. with a distance corresponding to several interior diametersof the following pipe 1B. On the other hand cases may also becontemplated where a favorable position of the measuring device is at aradial section or plane through the outgoing flow channels 7B. Stillanother possibility is to have such measuring devices located at two ormore positions within the range of distances mentioned here, so that ameasuring device for the measurement or the measuring situation, can beselected by the operator.

In the case of a single phase flow where the density and viscosity ofthe fluid are known, velocity measurement can be performed directlyaccording to equation (5) above, without the fraction measurementdescribed.

In the embodiment shown in FIG. 1-3 there are described flow channelsboth upstream and downstream of the regulating elements 4 and 5. Forsome applications it may be sufficient to arrange pairs of cooperatingflow channels 7A and 7B only at the outlet or downstream side, whereasthe two regulating elements 4 and 5 at the upstream side must then beprovided with large through flow openings corresponding approximately tothe flow cross section of inlet opening 22, i.e. also corresponding tothe lateral bores 4A, 4B and 5A, 5B respectively in both regulatingelements, as described above. As an alternative flow channels at theinlet side can be provided only in one of the two regulating elements.

Another possible modification is to provide more than two co-axialregulating elements, such as a third and perhaps quite thin walledregulating element between the two elements being described and shown inthe first embodiment of FIG. 1-3 of the drawings.

Whereas the embodiment described above is based on rotational symmetry,the embodiment of FIG. 4-6 in principle is a planar arrangement of theregulating elements. In FIG. 4 only the downstream portion is shown of ahousing 12 with two cooperating regulating elements 14 and 15, and afollowing outlet opening 33 that can e.g. be coupled to a pipeconnection in a similar manner as outlet opening 23 in FIG. 1. Arrow F4in FIG. 4 shows the direction of through flow.

At the top of the two (cut off) regulating elements 14 and 15 there arearrows showing the possibilities of displacing these elements. Thuselements 14 and 15 are arranged to be moveable in slits 13 in housing12. See also FIG. 5.

Through regulating elements 14 and 15 there are provided a number offlow channels, of which one such channel 17 is indicated in FIG. 4, 5and 6.

While the plate-like regulating element 15 is relatively thick, it ispreferred that the cooperating element 14 is relatively thin, wherebythe length of the individual flow channels 17 are determinedsubstantially by the thickness of element 15. In the embodiment shownhere the flow cross-sectional area of each channel 17 is adapted to becontrolled simultaneously along the whole length of the channel. This isobtained by means of a tongue-like plate piece 14B which protrudes fromthe regulating element 14 into each channel 17 and forms one of theboundary surfaces thereof. In this connection it will be realized thateach flow channel 17 most conveniently has a rectangular cross-sectionalshape, so that a sufficiently good seal between the side edges of tonguepiece 14B and the adjoining channel walls is obtained. FIG. 4 showselements 14 and 15 in a mutual position where somewhat more than half ofthe maximum cross-sectional area of each channel 17 is open for fluidflow. FIG. 6 shows the maximum open position of elements 14 and 15,where tongue piece 14B with its inner side (upper side) is brought intoengagement with one (upper) wall of the opening in element 15, whichinitially forms the flow channel 17.

In a complete mixer according to the invention a mixing chamber inhousing 12 (at the right hand side of elements 14 and 15 in FIG. 4)normally will also have a further, corresponding set of regulatingelements at the upstream or inlet side (not shown) in full analogy tothe first and circular embodiment of FIGS. 1-3. As the first embodimentalso the one in FIG. 4 has large bores 14A and 15A which uponappropriate displacement of elements 14 and 15 can be brought in linewith the outlet opening 33, in particular for the purpose of pigging, asalso explained in connection with the first embodiment above. Formaximum opening in that case, elements 14 and 15 ought to be mutuallydisplaced to a maximum open position as shown in FIG. 6, so that bores14A and 15A will be completely aligned with each other. In contrast tothe embodiment of FIGS. 1-3 the four regulating elements in such a mixercan be displaced and adjusted individually and independently of eachother. In certain circumstances this can be an advantage.

Although the plate- or slide-like regulating elements 14 and 15 havebeen referred to as planar, the fundamental manner of function willstill be the same if they were designed with a certain curvature, i.e.preferably with a curvature in the plane corresponding to the section ofFIG. 5. The mutual displacement of elements 14 and 15 by translationalmovement, will be possible also in the latter case.

It will also be possible to modify the embodiment of FIGS. 1-3 so thatthis by translational movement, i.e. parallel to the axis AX, canprovide for regulation of flow channels 6A-6B and 7A-7B respectively.For obtaining the pigging position, however, a rotary movement must beeffected as explained previously. This modification can be seen fromFIG. 8, where the whole design corresponds to FIG. 1 except for theinner regulating element 4X. This element is designed so as to makepossible a certain axial translational movement, as illustrated witharrow BX.

Finally, it will be realized that the flow channels both in the firstembodiment in FIGS. 1-3 and in the second embodiment of FIGS. 4-6, canbe designed with a varying cross-sectional area, possiblycross-sectional shape, along its whole length or parts thereof. Thus, inFIG. 10 there is shown a modified outer regulating element 5D havingconically narrowing channels 6D upstream and conically expandingchannels 7D downstream. In other respects this embodiments correspond tothe one in FIGS. 1 and 2. Moreover, the downstream portion of such flowchannels can be provided with nozzle-like restrictions. Still anothermodification of the embodiment of FIGS. 1-3 and FIG. 10 consists in thevariation of the flow cross-section along the whole length of thechannels, by means of tongue-like plate pieces at one regulatingelement, as described for the embodiment of FIGS. 4-6. Such amodification of the first embodiment can also be implemented on thebasis of a mutual rotation of the two regulating elements for adjustmentof the flow conditions.

In the modified embodiment of FIG. 7, which is intended for use as agas-liquid distributor in a freezing plant or heat pump system, theoutlet comprises a number of outlet channels 34A, 34B, 34C to be lead toan evaporator with several inlets. These inlets correspond to the numberof separate outlet channels 34A-C. There is here the question of aspecific channel or pipe branching for the purpose of connection torespective evaporator inlets.

We claim:
 1. Mixer for mixing the components of a fluid flow in a pipeconnection, comprising a housing adapted to be inserted in the pipeconnection for permitting fluid to flow therethrough in a flowdirection, said housing comprising an inlet opening and an outletopening each having a cross-sectional area, wherein the housing isprovided with a first moveable regulating element formed with athrough-bore and partially enclosing a central chamber, the firstregulating element having a first wall portion directed in a normaloperating position substantially toward the inlet opening on an upstreamside of said housing and a second wall portion directed in said normaloperating position substantially toward the outlet opening on adownstream side of said housing, said first wall portion being providedwith a plurality of ingoing flow channels, and said second wall portionbeing provided with a plurality of outgoing flow channels and whereinthe through-bore has a cross-sectional area corresponding substantiallyto the cross-sectional area of each of the inlet and outlet openings,said flow channels each having a substantially smaller cross-sectionalarea than the cross-sectional area of each of the inlet and outletopenings respectively, and wherein the first regulating element ismoveable in relation to said housing for selectively orienting part ofthe ingoing and outgoing flow channels toward the inlet opening and theoutlet opening, respectively, and part of said flow channels toward thehousing, whereby mixing is effected in the central chamber, between theinlet opening and the outlet opening and wherein the first regulatingelement is selectively movable to align the through-bore with the inletand outlet openings for a substantially free through-flow without mixingeffect.
 2. Mixer according to claim 1, wherein said housing has internalwalls substantially defining rotational surfaces broken by said inletand outlet openings respectively, said first regulating element beingco-axial with and rotatable in the housing, and being shaped as arotational body having a common axis with the housing, said common axisbeing oriented laterally relative to the flow direction, at least one ofsaid ingoing and outgoing flow channels being substantially radial tothe common axis and oriented by rotation of the first regulating elementto face one of the inlet and outlet openings and upon said rotationselectively to be blocked from said inlet and outlet openings by thehousing.
 3. Mixer according to claim 2, wherein said housing interiorlycomprises a central core member partially enclosed by said firstregulating element, the core member having a through-bore aligned withand having a flow cross-sectional area substantially equal to thecross-sectional area of the inlet and outlet openings respectively. 4.Mixer according to claim 1, wherein said first regulating element isrotatable in the housing and said through-bore extends through saidfirst regulating element to open at diametrically opposite wallportions, the through-bore being oriented at approximately 90°, about acommon rotational axis with said housing and said first regulatingelement, from said wall portions having said outgoing flow channels. 5.Mixer according to claim 1, wherein at least some of said flow channelshave varying cross-sectional areas, along at least part of their length.6. Mixer according to claim 1, further comprising structures subdividingsaid outlet opening to define a number of outlet channels, whereby themixer is applicable to one of a freezing plant and a heat pump systemhaving an evaporator with a corresponding number of evaporator inlets.7. Mixer according to claim 1 further comprising a measuring apparatuscomprising a differential pressure sensor coupled to the housing formeasuring a pressure drop at least partially over a flow path betweenthe inlet opening and the outlet opening, for use in calculating massflow.
 8. Mixer according to claim 7, wherein the differential pressuresensor is coupled to measure the pressure drop between the centralchamber and said outlet opening.
 9. Mixer according to claim 7, furthercomprising a fraction measuring device coupled to said outlet openingfor measuring a multi-phase flow.
 10. Mixer for mixing the components ofa fluid flow in a pipe connection, comprising a housing adapted to beinserted in the pipe connection for permitting fluid to flowtherethrough in a flow direction, said housing comprising an inletopening and an outlet opening each having a cross-sectional area,wherein the housing is provided with at least first and secondregulating elements partially enclosing a central chamber, each of saidfirst and second regulating elements having a first wall portiondirected in a normal operating position substantially toward the inletopening on an upstream side of said housing and a second wall portiondirected in said normal operating position substantially toward theoutlet opening on a downstream side of said housing, said first andsecond wall portions being provided with a plurality of ingoing andoutgoing flow channels, respectively, said flow channels each having asubstantially smaller cross-sectional area than the cross-sectional areaof the inlet and outlet openings respectively, the first and secondregulating elements being moveable in relation to said housing forselectively orienting part of the ingoing and outgoing flow channelstoward the inlet opening and the outlet opening, respectively andindividually mutually displaceable laterally relative to the fluid flowfor selectively opening and closing serial flow channels defined by theregulating elements and passing from the inlet opening, throughselectively aligned ones of the ingoing flow channels of the regulatingelements, through the central chamber, and through selectively alignedones of the outgoing flow channels of the regulating elements to theoutlet opening, whereby mixing is effected in the central chamber,between the inlet opening and the outlet opening.
 11. Mixer according toclaim 10, wherein said housing has internal walls substantially definingrotational surfaces broken by said inlet and outlet openingsrespectively, said first and second regulating elements being co-axialwith and rotatable in the housing and relative to one another, theregulating elements being shaped as rotational bodies having a commonaxis with the housing, said common axis being oriented laterallyrelative to the flow direction, at least one of said ingoing andoutgoing flow channels being substantially radial to the common axis andoriented by rotation of the respective one of the first and secondregulating elements to face one of the inlet and outlet openings andupon said rotation selectively to be blocked from said inlet and outletopenings by the housing, wherein said at least first and secondregulating elements partially enclose each other, said wall portionswith said flow channels having mutual fluid sealing such that saidmovable regulating elements are rotatable to assume a position in whichat least some of said ingoing and outgoing flow channels in one saidregulating element are aligned with said flow channels in another saidregulating element.
 12. Mixer according to claim 11, wherein said firstand second regulating elements are individually rotatable for mutualdisplacement of the regulating elements.
 13. Mixer according to claim11, wherein said first and second regulating elements are coupled withrotating coaxial spindles extending to a same side of said housing. 14.Mixer according to claim 10, wherein said first and second regulatingelements are mutually displaceable in an axial direction for aligningthe ingoing and outgoing flow channels.
 15. Mixer according to claim 10,wherein said first and second regulating elements are plate-shaped andare mutually displaceable by translational movement.
 16. Mixer accordingto claim 15, wherein the first and second regulating elements comprisetwo adjacent regulating elements at said upstream side for said inletopening and two adjacent regulating elements at said downstream side forsaid outlet opening, and wherein each said adjacent regulating elementis individually displaceable.
 17. Mixer according to claim 10, whereinsaid ingoing and outgoing flow channels of said first and secondregulating elements open at said first and second wall portions onsubstantially diametrically opposite upstream and downstream sides, atleast the ingoing flow channels being generally radial and each having across-sectional area substantially smaller than the cross-sectional areaof the inlet and outlet openings respectively, such that flow convergesin the central chamber.
 18. Mixer according to claim 17, wherein each ofsaid first and second regulating elements are provided with ingoing flowchannels, and wherein at least some of the ingoing flow channels in oneof said first and second regulating elements are alignable in oneangular position with the ingoing flow channels in the other of saidsecond first and second regulating elements.
 19. Mixer according toclaim 18, wherein at least some of the flow channels in one of saidfirst and second regulating elements have a larger cross-sectional areathan at least some of the flow channels in another of said first andsecond regulating elements.
 20. Mixer according to claim 17, whereinsaid outgoing flow channels are substantially parallel to each other andare regularly distributed over said wall portions of said first andsecond regulating elements.
 21. Mixer according to claim 10, wherein atleast one of said first and second regulating elements comprises a platepiece having tongue-like pieces extending into the flow channels along asubstantial length of an internal cross-section of the flow channels ofthe other of the first and second regulating elements, wherebydisplacement of one of said first and second regulating elementsregulates the internal cross-sectional area of said flow channels ofsaid other of the first and second regulating elements along saidsubstantial length.
 22. Mixer according to claim 21, wherein said platepiece is relatively thin and said tongue-like pieces protrude into andform a longitudinal boundary surface through substantially a wholelength of the flow channels in another of said first and secondregulating elements, and wherein said flow channels have a rectangularcross-sectional shape.